PLATE VII. 



Fin. 12.— Antispadix, viewed from the outer side. Nearly twice natural size. 

 G, slime gland upon the sheath of the antispadix. 



F, projecting Hap of the sheath, partly covering the fourth tentacle. 

 4, fourth tentacle. 



p IG _ 13.— Spadix, viewed from the inner side. The loose integument covering its base has been cut away. 

 Natural size. 



1, first cirrus. 



2, second cirrus. 



3, third cirrus. 



Fio. 14. — Spadix, viewed from the outer side. Natural size. 



G, slime gland of the sheath. 



SH, line along which the integument has been cut away to expose the base of the spadix. 



1, first cirrus. 



2, second cirrus. 



3, third cirrus. 



4, fourth cirrus, nearly covered by the projecting flap of the spadix sheath. 

 Fig. 15.— First cirrus of the spadix. Nearly natural size. 



Fig. 16. — Second cirrus of the spadix, viewed from the ventral side. Natural size. 



Fig. 17. — Third cirrus of the spadix, viewed from the dorsal side. Natural size. 



Fi«. 18. — Third cirrus of the spadix, viewed from the ventral side. Natural size. 



Fig. 19. — Fourth cirrus of the spadix. Natural size. 



Fig. 20.— Lamellated organ upon the median portion of the inferior labial lobe of the female, viewed from the dorsal 



side. Twice natural size. 

 Fio. 21. — Rhinophore, viewed from the anterior side. X 3. 



DP, aperture of the dorsal pit. 



F, aperture of the fossa. 

 Fig. 22. — Longitudinal section of the rhinophore passing through the fossa and the tentacle. 



a, nerve. 



1>. c, portions of the fossa, c is near the opening of the fossa to the exterior. The section does not extend to 

 the closed central end of the fossa. The heavy outer line indicates the extent of the external epithelium. 

 Only as much of the rhinophore as is bounded by this line extends beyond the surface of the body. 

 Fio. 23. — Cross section through the middle of a gill. X 2. 



1, branchial vein. 



2, branchial artery. 



3, stem of gill. 



4, respiratory membrane of leaflet. 



5, supporting portion of leaflet. 



Fig. 24. — Lamellated region upon the inner surface of the cephalic sheath of the female, just back of the ventral 

 notch, which forms an organ for receiving the spermatophore. Below the lamellated region the tip of the 

 funnel is seen; at the sides, some of the most ventral digital tentacles. Twice natural size. 



Fig. 2o. — Spermatophore in situ upon the lamellated receiving region. Natural size. 



Fig. 26. — Base of the inferior labial lobe of the female, seen from the dorsal side. X 2. 



1, 1', levator muscles. 



2, 2', approximator muscles. 



3, 4, 3', 4', lateral retractor muscles. 

 5, dorsal median retractor muscle. 



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